A planetary gear mechanism applied to an automatic transmission and a center differential includes a plurality of pinion gears geared with a sun gear and ring gears and a carrier for supporting the plural pinion gears. An external peripheral surface of the pinion gear is formed with teeth engaged with a tooth flank of the sun gear and the ring hears. An internal peripheral surface of the pinion gear inserted with is a pinion pin to be relatively rotatable via rolling bearing.
A known planetary gear mechanism is disclosed in Japanese Utility Model Registered No. 2508622. The known planetary gear disclosed in Japanese Utility Model Registered No. 2508622 is shown in FIGS. 5-6.
As shown in FIGS. 5-6, a planetary gear mechanism 120 includes a sun gear 121, a ring gear 123, four planetary gears geared with the sun gear 121 and the ring gear 123, a carrier 125 for supporting the planetary gears 122 so that the planetary gears 122 rotate about the sun gear 121, four pinion pins 126, one end portion of each pinion pin 126 is inserted into a shaft bore portion formed on the carrier for rotatably supporting the respective planetary gears 122, and a plate shaped stopper 134 unitary provided on the carrier 125 for fixing the pinion pins 126.
A recess groove is formed on an end portion of each pinion pin 126. The stopper 134 is provided with four fitting portions 134c fitting in the respective recess grooves by adjusting a phase of the stopper 134 for restricting the axial and rotational movement of the pinion pin 126. Four bent portions 134b are formed on an external periphery of the stopper 134. The movement of the stopper 134 relative to the carrier 125 in the axial direction is restricted by covering convex portions 125i formed on the external periphery of the carrier 125 wrapping with the bent portions 134b. Further, the rotational movement of the stopper 134 relative to the carrier 125 is restricted by fitting convex portions 125j and the convex portions 125i and the bent portion 134b alternately between adjacent projecting portions 124e of input case 124 of the planetary gear mechanism 120.
Notwithstanding, because the bent portions 134b of the stopper 134 are required to be wrap the external periphery of the convex portions 125i of the carrier 125 in order to restrict the axial and rotational movement of the stopper 134 relative to the carrier 125, the bent portions 134b are required to be bent to be conformed to the convex portions 125i. Thus, complicated operation is required at assembling. Although the bent portions 134b may be formed in advance for assembling the stopper 134 by rotating after fitting the pinion pins 126 in the planetary gears 122, the stopper 134 cannot be assembled to the carrier 124 when the rotational directional position of the stopper 134 relative to the carrier 125 is deviated because the carrier 125 defines the position of the stopper 134 in the rotational direction. Thus, this method is not favorable for assembling.
A need thus exists for a planetary gear mechanism which includes favorable assembling performance.